Brake pipe vent valve for locomotive brake system

Abstract

The present locomotive brake system includes a brake controller operable by an operator and a brake pipe vent valve. The brake controller includes an emergency output port which provides emergency pneumatic signal on the emergency output port when the brake controller is in an emergency position. The brake pipe vent valve includes a housing having brake pipe, emergency input and exhaust ports, and a first valve. The emergency output port is fluidly connected to the emergency input port. The first valve selectively connects the brake pipe port to the exhaust port when opened in response to an emergency signal on the brake pipe port and in response to an emergency signal on the emergency input port.

1 . A locomotive brake system comprising:
 a brake controller operable by an operator to generate brake signals and including an emergency output port which provides an operator emergency pneumatic signal on the emergency output port when the brake controller is in an emergency position;   a brake valve responsive to brake signals from the brake controller for generating brake signals on a brake pipe;   a brake pipe vent valve including
 a housing having brake pipe, emergency input and exhaust ports, 
 a first valve for selectively connecting the brake pipe port to the exhaust port when opened in response to a greater pressure in a first volume than pressure in the second volume connected to the brake pipe port, the first and second volumes being connected by a choke, and in response to a smaller pressure in a third volume connected to the emergency input port than pressure in the first volume; and 
   the emergency output port of the brake controller being fluidly connected to the emergency input port of the brake pipe vent valve.   
   
   
       2 . The locomotive brake control according to  claim 1 , wherein the first and second volumes are separated by a diaphragm and an stem connected to the diaphragm engages a valve element of the first valve to move the valve element off a valve seat to open the first valve. 
   
   
       3 . The locomotive brake control according to  claim 2 , wherein the first and third volumes are separated by the valve element. 
   
   
       4 . The locomotive brake control according to  claim 2 , wherein including a spring biasing the valve element onto the valve seat. 
   
   
       5 . A locomotive brake system comprising:
 a brake controller operable by an operator to generate brake signals and including an emergency output port which provides an operator emergency pneumatic signal on the emergency output port when the brake controller is in an emergency position;   a brake valve responsive to brake signals from the brake controller for generating brake signals on a brake pipe;   a brake pipe vent valve including
 a housing having brake pipe, emergency input and exhaust ports, 
 a first valve for selectively connecting the brake pipe port to the exhaust port when opened in response to an emergency signal on the brake pipe port and in response to an operator emergency signal on the emergency input port; and 
   the emergency output port of the brake controller being fluidly connected to the emergency input port of the brake pipe vent valve and the brake pipe port of the brake pipe vent valve being fluidly connected to the brake pipe.   
   
   
       6 . The locomotive brake control according to  claim 5 , wherein the first valve opens in response to a greater pressure in a first volume connected to a second volume by a choke than pressure in the second volume connected to the brake pipe port and opens in response to a smaller pressure in a third volume connected to the emergency input port than pressure in the first volume. 
   
   
       7 . The locomotive brake control according to  claim 6 , wherein the first and second volumes are separated by a diaphragm and an stem connected to the diaphragm engages a valve element of the first valve to move the valve element off a valve seat to open the first valve. 
   
   
       8 . The locomotive brake control according to  claim 7 , wherein the first and third volumes are separated by the valve element. 
   
   
       9 . The locomotive brake control according to  claim 7 , wherein including a spring biasing the valve element onto the valve seat. 
   
   
       10 . A brake pipe vent valve for a locomotive, the valve comprising:
 a housing having brake pipe, emergency input and exhaust ports;   a first valve for selectively connecting the brake pipe port to the exhaust port when opened in response to an emergency signal on the brake pipe port and in response to an operator emergency signal on the emergency input port;   wherein the brake pipe port is to be connect to the brake pipe and the emergency input port is to be connected to an emergency output port of a brake controller.   
   
   
       11 . The valve according to  claim 10 , wherein the first valve opens in response to a greater pressure in a first volume connected to a second volume by a choke than pressure in the second volume connected to the brake pipe port and opens in response to a smaller pressure in a third volume connected to the emergency input port than in the first volume. 
   
   
       12 . The valve according to  claim 10 , wherein the first and second volumes are separated by a diaphragm and an stem connected to the diaphragm engages a valve element of the first valve to move the valve element off a valve seat to open the first valve. 
   
   
       13 . The valve according to  claim 12 , wherein the first and third volumes are separated by the valve element. 
   
   
       14 . The valve according to  claim 12 , wherein including a spring biasing the valve element onto the valve seat.